James Prescott
Joule was the fourth born son to Benjamin and Alice Joule on Dec
24, 1818 in Salford, Great Britain. The first two boys the
Joules had both died in infancy. The thirdborn child was James
brother Benjamin (b. 1817) named after his father. James was followed by
two sisters Alice (b. 1820) who died at the age of 14 and Mary
(b. 1823). He also had a younger brother John (b. 1824).
James father Benjamin, was a wealthy man who established a
brewery in Manchester near a prison
begun by John Howard (as in the John Howard Society).
James spent much of his childhood (ages 5 - 12) in ill health due to a
spinal weakness however through some unorthodox procedures by the brothers
Taylor, who started their careers as horse doctors, James improved such that
most of his youth he was fairly well. The illness had a greater impact on James
psychologically, making him quite shy and unassertive when in the presence of
others. James and his brother Benjamin were quite close though out their early
lives. James did not receive a normal schooling, instead he and his
brother Benjamin were tutored at home by a series of tutors culminating
with John
Dalton. Indications are that much of James education was
self administered.

EARLY INTERESTS:James early influences included an interest in trains (steam engines)
as well as the steam powered devices of his fathers brewery. He had a
boyhood interest in steam locomotives which may have sparked his interest in
the field of thermodynamics. Ironically, Joule was involved in a train accident
himself in which three people were killed.
The brothers Joule took an interest in phenomena such as lightning and the
aurora borealis which they discussed at length with their tutor John Dalton.
The boys also sounded or measured the depth of Lake Windemere to be
198 feet (today known to be 220 feet). James lost his
fathers cavalry pistol while investigating an echo in the mountains .
This was not his only encounter with weapons, on another occasion he
accidentally blew off his eyebrows.
James also had a somewhat scary disregard for the servants health at the
Joule residence. He carried out a series of tests on a servant girl giving her
a series of shocks until ultimately she lost consciousness. James decided that
this would be an appropriate point to conclude his experiment. (Lucky for the
servant girl.)
Although James did work at his fathers brewery his interest lied in
experimentation which at first was spontaneous in nature. John Dalton who
instilled in James the need to be a meticulous experimenter. Dalton did little
more than teach the Joule boys arithmetic and geometry however he did introduce
the boys to chemistry as was James fathers intention. Dalton
insisted on following a careful procedure and becoming very skilled in the use
of laboratory equipment.
James went on to be a much more renowned experimenter than his mentor,
combining skill, originality and ingenuity. For example, James constructed
instruments of measurement of a precise degree of accuracy, for the time in
which he lived. Even by todays standards these instruments would be
considered quite accurate. He was quite adept at balancing theoretical
speculation and careful experimentation.

JOULES SERIOUS WORKOne of Joules early interests was in the field of electricity. He was
interested in improving the electric motor by making the electromagnet and
batteries more efficient. As a result of his experimentation Joule discovered
that the power of the engine was proportional to the product of the current and
the emf (battery intensity).
Joule eventually gave up on this line of experimentation since the steam engine
of the day was much more economical. Joule still felt that the electric motor
would someday replace the steam engine. It was after he reached this impasse
with the motor that Joule turned his attention to the relationship between
electricity and heat.
Much of Joules work took place between 1837 and 1847.
During this time Joule along with Hermann von
Helmholtz, Julius von Mayerand Lord
Kelvin
established the principle of conservation of energy which states that energy
used up in one form reappears in another form and is never lost.
One of his more serious experiments led to the following result: The amount of
heat produced by an electrical current is proportional to the product of the
resistance of the wire and the square of the current. (das war 1845)
Joule had a major association with William Thomson
(nicht der o.g. Graf Rumford oder Benjamin Thomson,
sondern einer der vielen anderen Thomsons, die in der Physik noch bekannt
sind) in which each helped the other refine their ideas.
It appears from the readings that Joule was the better of the two experimenters
in both the construction of lab equipment, execution of the experiment and in
the theoretical side of the experiments. However the combination of minds led
to greater accomplishments than had they not worked together. As a result of
their collaborative efforts they determined that when a gas expands without
performing work, its temperature falls. This became known as the Joule -
Thomson effect and its application was paramount to refrigeration
technology.
This collaboration of minds on research in a particular area was quite new and
different to the research practices of the day. Early on in his career he was
criticized for drawing conclusions based on his work that were not completely
justified by his workings. Joule took these criticisms to heart and although he
was noted for his experimental precision, he was also known to be cautious
about making speculations about the meaning of his results.
The last two years of Joules life were spent mainly in his house where he
spent the majority of his time reading . On Oct. 11th, 1889 Joule
succumbed to his illness, a form of degeneration of the brain. As was the case
of his life, he was honored for his achievements. His contributions in the
field of thermodynamics were great and influential to the future developments
in the field.